1. Field of the Invention
The instant disclosure relates to a light-guiding structure and a light-emitting device, and more particularly to a light-guiding structure and a light-emitting device for increasing the viewing angle (i.e., the illumination angle).
2. Description of Related Art
Because the LED (Light Emitting Diode) offers advantages of power savings, high emission efficiency and long life, it is widely used in various applications, such as traffic control devices, electronic billboards, light of transportation, flashlights, and illumination devices. One problem posed by use of an LED in an illumination device is that the characteristics of an LED are different from a conventional bulb. That is, a conventional bulb is a surface light source, while an LED is a point light source. Therefore, a conventional bulb can provide a 360 degree is viewing angle, but an LED can only provide a 120 to 140 degree viewing angle. Conventional techniques for overcoming this limitation include utilizing secondary optics, arranging the LEDs or polishing the lamp cover for covering the LEDs. However, even when utilizing secondary optics or providing a polished lamp cover, a conventional LED illumination device is still limited to providing a 160 degree viewing angle. People skilled in the art often arrange or assemble the LEDs to extend the viewing angle.